OAKLAND -- Nelson Cruz is a strong man, as evidenced again by a thunderous home run hit by the Mariners' designated hitter in Wednesday's 9-8 victory over the A's at Oakland Coliseum. But the big man has new company in that department as teammate Dae-Ho Lee ripped a pair of homers himself to propel Seattle to a series sweep.

Cruz reached the upper deck in straightaway center field -- rare territory, indeed -- on a shot off A's rookie left-hander Sean Manaea on a 1-0 fastball to give Seattle a 4-2 lead, only to see Oakland erupt for six runs off Felix Hernandez in the bottom of the fifth to take an 8-4 lead.

But that merely set the stage for Lee -- a 250-pound slugger from Korea -- to hit a solo shot to begin Seattle's comeback in the sixth and then a two-run bolt to provide the go-ahead runs in the seventh as the Mariners won for the 14th time in their past 19 games to maintain their slim lead over Texas atop the American League West.

"Those are the kind of wins that stick with you for a while," said manager Scott Servais. "The guys believed the whole time. When we got down, in the dugout there was never any doubt that we were going to get back in it. Today the offense will get the credit, no doubt. Pitching has carried us for the majority of the year, but our offense really stepped up."

Cruz, who finished second in the Majors with 44 homers last season, now has five on the year. And Lee is right behind him with four in just 32 at-bats as he's been used strictly in platoon situations against left-handed starters.

Must C: Lee's big homers

Must C Clutch: Lee clubs homers in comeback

Dae-Ho Lee connects on a pair of big home runs, including the go-ahead homer in the 7th, to give the Mariners a 9-8 victory over the A's

But Servais stuck with Lee in this one even when A's skipper Bob Melvin brought in right-handed reliever Ryan Dull to replace Manaea in the sixth, and Lee drove a first-pitch fastball over the fence in right-center, then did it one better with his two-run game-winner off another right-hander in John Axford the following inning.

"You do have to go by the numbers in this game, and I look at them closely," Servais said. "You prepare, and there are times you have a feeling. I thought it was an opportunity. We were down 8-4, and it's still relatively early in the game. Give Dae-Ho a chance, and obviously he squared up a big home run to get some momentum going.

"Then the at-bat against Axford, I talked to [hitting coach Edgar Martinez] about two innings before that because he could kind of see where that was coming. We just agreed to ride Dae-Ho. He had the great at-bat, worked himself into the fastball count and he didn't miss it."

"It doesn't make any difference, righty or lefty," said Lee, who hit 98 homers the past four years in Japan and once had 44 in a season playing in Korea. "Every at-bat is important to me."

As for Cruz's bolt, the big man downplayed the distance, saying it was "just another homer," even if his smile said otherwise. So, too, did his teammates.

"That was unbelievable," said Hernandez. "He said he's still got more in the tank, but I don't believe him. That was crushed."

Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.